Help with sleep/lock button

[jessie2sexy]

Yesterday, I bought an iPhone 4 for my girlfriend from a person off of craigslist. When I looked at it everything seemed to be fine and I didn't notice a problem with it until later on. The problem is that it was randomly locking for no reason and when I push the lock/sleep button, it locks the screen but instead of fading black and sleeping, it goes to the lockscreen(with the clock/slide to unlock) and then asks me to slide to power off or cancel, it does this everytime I push the lock button. I looked online and alot of people gave others the solution of restoring and updating it so I restored it to factory settings and updated to 6.1.3 but it is still doing. I kept playing with it and it doesnt appear to randomly lock anymore or atleast I hope so, but it DOES keep doing the slide to power off thing. Also, the lock button is very sensitive and it doesnt take much of a tap for it to do all of this. I was just wondering if you guys would happen to either know if it is just the lock button that is broke and if I replaced the lock button it would fix it or maybe if there was a app, perhaps on Cydia, that could make it where the lock/sleep button just doesn't do anything, because i can use AssistiveTouch to lock the screen. Aside from the whole lock button screen the phone is in pretty great condition and works like a charm. I will appreciate any help you guys can provide!

 

[gadgetrx.net]

It sounds like it could be a hardware issue (sensitive button and still persisting after a restore). The power flex cable could be physically broken or damaged causing this issue or one other thing. How the button works is that there is a little metal circle under the power button which in turn presses on another button on the power flex cable. Some times this circle gets off center and causes the button to press all the time or make it super sensitive.